Process for producing thin insulating layers upon wires



. J l u I Dec. 30 1930. R. RUDENBERG :TAL 1,736,920

lmocmss` Fog PnoDUcING THIN INSULATIG Lunas Uro!! WIRES Filed Jan.loflszs Patented Dec. 30, 1930 UNITED STATES PATENT oFF'ylpcE" nEINnoLDRUDENBERG, or BERLINGBUNEWALD, AND WALTER s cnorrxx, -orBERLIN-cHAaLo'rTENBURG, GERMANY, AssrGNoRs 'ro SIEMENS-sonnexnnrwnnxn iAKTIENGESELLSCHAFT, or BEaLIN's1EmENssTAIyr, GERMANY, A conroaArIoN OFGERMANY PROCESSEUR PBOD'UCING THIN INSULATING- LAYERS 'UPON WIRESApplication mea Jnnunyy 1o, 1.929,A serial No. 331,685, and in GermanyJanuary 1e, 192s.

'Our invention relates to an improved proces s for producing thininsulating layers upon w1res.

It has already been proposed to coat wires,

5 more particularly wires carrying'high-tension electric current, withinsulating substances consisting of thin layers or films, the

thickness of a plurality of these layers or films being less .than 0.01mm.

The object of our invention is an improved process of applying theselayers or films to wires. Our improved process consists substantially indirectingthe vaporized insulating substance, preferably under a vacuum,

against the wire to be insulated and-precipi- 2@ passed and from whichthe vapor of the in-' tating it there in the form vof .a thin layer orfilm. In reducing our invention to practice we preferably employ anannular nozzle. through which the Wire to loe insulated is sulatingmedium issues.l Part or' the vapor is then precipitated upon the wire.The thickness of the insulating layer may be varied within wide limitsby altering the speed of the wire. l

To apply ,a plurality of insulating layers or iilins to the wire, it isnecessary to repeat the process describeda number of times. As ithasbeen ascertained that the dielectric 3@ strength of the insulationincreases considerably'if the layerso different materials alternate,preferably layers of different insulating substances, it 1s according toour improved process possible to coat the wire in a single continuousoperation with a plurality of layers or films of diderent insulatingmaterials/ by drawing it successively through a number of the applyingdevices of the kind described. Y l

By means or our improved process not insulating layers only, but alsolayers of metals tension transmission lines, hundreds of such thin filmshave to be applied to the conductor. It is then necessary to provide acorresponding number of nozzles one behind the other. The apparatus forcarrying out this r 'process then'requires considerable s ace.

This trouble maybe avoided by assing the conductor slowly pastv one or ap urality of nozzles, the conductor and the nozzles re'volying ata highspeed in opposite directions. If,

for instance, a single nozzle only is employed a` layer or coat isformed on the surface of the wire during one revolution and during thenext revolution a further layer, which according to the feeding speed ofthe wire overlaps the underlying layer more or less, or in other words,the nozzle produces upon the conductor a thin insulating band of adefinite width, which overlaps andl winds itself upon the condutor-inthe form of a helix. If more than one nozzle is employed multiplehelixes withv overlapping layers in `the form of bands are obtained.Each nozzle may either spray the same insulating substance against thesurface of the conductor or an insulating substance of diiferent naturemay be used for each nozzle.

In the drawing affixed hereto and forming part of our specication anapparatus for carrying out oui-.improved process is illustrated by wayof example.

Referring to this drawing, 1 is a wire,

which is slowly drawn between the nozzles 3, 4 located upon the ring 2.The nozzles rotate at a high speed around the axis of the wire andproject the insulating substance in the form of a vapor or in anatomized ,state against the surface of the wire. To' accelerate thecondensation of the Vapor the Wire is first passed through a tank 5filled with liquid a1r or other cooling agent. After the wire has passedbeyondthe nozzles it is covered with a plurallty of layers or thininsulating lms', ,which as roughly indicated in vthe drawing overlap orare superposed 1n the manner of roongtiles.'

If 1000 superposed layers for instance, should be applied to the wire,the nozzles 'are adapted to rotate at a speed of 3000 `revolutions perminute and if each nozzle produces an insulating band of 8 inches theWire l is drawn through between the nozzles at a speed of 2 feet perminute.- If the bands produced by the nozzles are narrower the speed ofthe Wire must be correspondingly reduced. This also applies if thenumber of revolutions of the nozzles is smaller. By regulating the Widthof the band, the number of revolutions of the nozzles and the rate offeed of the Wire, coats of any desired number of layers may be obtainedupon the Wire. Should the speed of travel of the Wire then become toolow, the wire may be pulled in succession through a plurality lofdevices of the described kind.

As already pointed out our improved process is preferably carriedl outin a vacuum chamber or at least in 'an atmosphere comparatively freefrom dust to prevent breaks in the continuity of the layer caused .byparticles of dust deposited. When Work` ing in a vacuum the furtheradvantage is obtained, that the insulating material need not y be raisedto a particularly high temperature', because at the one hand itevaporates at a lower temperature than atmospheric pressure and at theother hand cooling of the stream of vapor by conduction is avoided.

Various modifications andchanges may be made Without departing from thespirit and the scope of the invention.

We claim as our invention:

1. In thel process of producing thin insulating layers of less than 0.01mm. thickness upon Wires, the alternate precipitation ofdiferent'insulating substances from the gaseous state upon the surfaceof the Wire.

2. In the process of producing thin insulating layers of less than 0.01mm. thickness upon Wires, the alternate precipitation of differentinsulating substances from the .gaseous state upon the surface of thestrongly cooled wire.

3. In the process of producing thin insulating layers of less than 0.01mm. thickness upon Wires, the alternate precipitation of differentinsulating substances from the gaseous state under a vacuum upon thesurface of the Wire. n

4. In the process of producing thin insulating layers of less than 0.01nim. thickness upon Wires, the alternate precipitation of differentinsulating substances from the gas.- eous state under a vacuum` upon thesurface of the strongly cooled wire.

t 'In` testimony whereof We ax our signaures. 4

REINHOLD annemasse. WALTER scnorrnv.

